That’s better. I’ve been sharply reminded of the clandestine exploits of Bruce Wayne and his, excuse me, “ward” Dick Grayson but not for those reasons. While it’s true that I’m not actually a millionaire recluse who secretly dons figure-hugging lycra to become a closet caped-crusading crime-fighter, the time has come to break the silence: I lead a double life.

I’m not alone… but you never spot us. By day we pass innocently as men and women going about our business, infiltrating every conceivable profession in devilishly maintained guises as civil servants, management consultants, music producers, teachers, editors, publicists, solicitors, a barrister, a banker, a doctor, a restaurant manager, a movie special effects designer, a language tutor-cum-screenwriter, a recovering estate agent and a trainee vintner. On Mondays, however, under the cover of twilight, we undergo rigorous training in a top-secret location (the Swiss Church, Endell St, Covent Garden, since you ask). It may sound parochial but, like Thunderbirds, our reach is international. Hell, our most recent operation climaxed in Estonia. What did we do there? We sang.

No, not like canaries – I’m not talking ‘political informer’. Nor does my hitherto hidden life quite embody Burgess-and-MacLean-scale duplicity. My parallel existence hasn’t taken me to Russia (yet) but each week I am catapulted from mundane reality into a different world because unbeknownst to all but my closest comrades I sing second bass in a chamber choir.

Despite my upbringing as a nice-ish Jew-ish boy, I’ve always had a seriously soft spot for Christmas carols – early exposure as a boy treble in annual concerts in St. Martin’s-in-the-Fields left its mark. But three winters ago I found myself in Cardiff covering a competition for The Singer magazine. Having fessed up to my vocal past, one of the organisers told me about Coro, a London-based choir she co-ran. With the lure of lush Christmas music being sung beneath the Christmas tree in Trafalgar Square in aid of Amnesty International, I was in like Flynn.

When I gave up acting over a decade ago, my singing went with it. I’d lent my once trusty, now rusty voice to the odd occasion when friends needed a little bass ballast and had once briefly flirted with another London choir – there are plenty once you start looking – but nothing had ever gelled into anything serious. But something happened that chilly Saturday afternoon beyond facing out the dilemma of “Do I wear gloves and lose the ability to turn the music pages or discard the gloves and entertain frostbite” I fell headlong back in love.

The absolutely physical joy of singing is simply incomparable. Even the undoubted, unashamed exhilaration of an actor’s curtain-call comes a poor second to the dizzying pleasure of being surrounded by the harmony of other unaccompanied voices clustered around you all equally dedicated to lifting printed dots into audible, thrilling life. But then singing is nothing less than, quite literally, breathing art.

Practising atheist that I am, it strikes me that for all the centuries of music written to be sung in church or at the very least in praise of God, combining one’s physical and mental energies into so beautiful an act has nothing to do with religion and everything to do with humanity at its most profoundly selfless. What could be more human than a bunch of people shedding their ordinary lives once a week to make music by just opening their throats… and then piling into the pub to pour beer down them? Which brings me to Estonia, which turns out to be the modish destination of the more intrepid of English stag nights thanks to the plentiful supply of pleasingly inexpensive alcohol, much of which Coro felt it only polite to sample.

So there we are in the shockingly unspoilt, medieval walled city of Tallinn bedizened with cobbled streets, pepperpot towers, pewter steeples and higgledy-piggledy, fairy-tale houses. It’s cold enough for the Baltic to have frozen over beneath a textbook-blue sky but we bask in surprisingly radiant April sunshine. That is, when not rehearsing for our first round appearance in the 8th International Choral Competition in a country that takes singing so seriously, the national concert hall is on the banknotes.

Unfortunately, we discover that the competition boasts 45 choirs from around the world. Ah. These include competitors from music academies, people who sing every day. Coro comprises 24 of us plus our new conductor Mark Griffiths and together we’ve done just 14 Mondays plus one concert. Which explains the amount of air-punching and leaping that accompanied Mark’s announcement, four days later, that along with just five others, we’re into the final… starting in 50 minutes.

We opened with Finzi’s tiny but mighty ode to joy My spirit sang all day and as the last exultant chord rang out across the hushed hall I realised I felt as if I were flying. Mark had brought us to the boil at exactly the right moment. Alert but relaxed, we were listening to each other and singing better than we ever had before. Even Giles Swayne’s fiendish, African-inspired Magnificat with 12 separate voice parts simultaneously running against each other suddenly sounded like music rather than a technical exercise.

It was, basically, a matchless blast. Nothing, however, prepared us for the judges’ announcement five hours later to the jam-packed hall that the winner of the Grand Prix was… Coro. A bolt of pure, red-hot joy lifted me clear out of my seat. No single moment of my adult life has touched that feeling. We yelled the place down, rushed on stage to receive our prize, belted out an encore of a ten-part arrangement of Joshua fought the battle of Jericho and the audience went bananas. Two weeks later we were back in Covent Garden, rehearsing a new programme. With apologies to Bob Geldof, I do like Mondays.